Mine spools at idle on cold start program with the turbo side. I mean, really noticeable. If you don't like spooly goodness don't buy one or at a minimum, don't go turbo side. If you want to turn heads though - you'll love it Going under a decent bridge or tunnel, it sounds absolutely awesome together with my 2.5" twin S/S crackling away at WOT. I think for spool noise out of a low mount - nothing comes close.